In various communication systems a receiver down-converts signals received from a transmitter to baseband. The receiver typically adjusts the down-conversion frequency using automatic frequency control (AFC) techniques. The signal to noise ratio (SNR) of the received signal is a dominant factor affecting the tracking capabilities of the AFC.
A “coverage enhancement” mode has been introduced in Release 13 of the Long Term Evolution (LTE) 3GPP specifications for extending the cell coverage area. A related study on coverage enhancement was earlier reported in 3GPP Technical Specification 36.888, entitled “Technical Specification Group Radio Access Network; Study on provision of low-cost Machine-Type Communications (MTC) User Equipments (UEs) based on LTE,” (3GPP TR 36.888, version 12.0.0, Release 12), May, 2013, whose disclosure is incorporated herein by reference.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.